Therapeutic vaccines and cancer: focus on DPX-0907

Figures & data

Table 1 TAA peptides included as antigens in DPX-0907 therapeutic cancer vaccine and their sequences and species homologies

Peptide	Gene	Sequence	Over peptide	Peptide + flank	Protein	Range
P7
Human	ABI_2	RYIRKPIDYTILDDIGHGVKWLLRFKVST				135–163
Mouse	ABI_2	RYIRKPIDYTILDDIGHGVKVSTQNMKMG	100	79.3	86.35	135–163
P13
Human	ADA17	GRGEESTTTNYLIELIDRVDDIYRNTSWD				240–268
Mouse	ADA17	GRGEESTTTNYLIELIDRVDDIYRNTSWD	100	100	91.9	240–268
P3
Human	BAP31	LKKGAAVDGGKLDVGNAEVKLEEENRSLK				157–185
Mouse	Bap31	LKKGAAEDGDKLDIGNTEMKLE-ENKSLK	60	75	90.24	551–581
P15
Human	DDR1	QRPPFSQLHRFLAEDALNTV-NH3				894–913
Mouse	DDR1	QRPPFAQLHRFLADDALNTV-NH3	90	90.2	93.44	892–911
P5
Human	ITGB8	AILDQCKTSCALMEQQHYVDQTSECFSSP				652–680
Mouse	*	SLHWVNDLPRAL-EQIHYVLKPDGVFVGA	77	<60	NA	160–187
P14
Human	JUP	COOH-MEVMNLMEQPIKVTEWQQTYTYD				1–23
Mouse	Jup	COOH-MEVMNLIEQPIKVTEWQQTYTYD	90	95.65	96.78	1–23
P4
Human	TOP2A	FPPKDDHTLKFLYDDNQRVEPEWYIPIIP				817–845
Mouse	Top2a	FPPKDDHTLRFLYDDNQRVEPEWYNPINT	100	86.21	89.06	818–836

Notes:

* Probable methyltransferase C20orf7 homolog; underlined human sequences represent the peptides included in DPX-0907; bold letters indicate substitutions in mouse relative to human sequence; dash (−) indicates a deletion relative to other strand.

Abbreviations: ABI_2, Abl-binding protein 3C; ADA17, TACE/ADAM-17; BAP31, BAP31/CDM protein; DDR1, EDDRI; DPX, DepoVax™; ITGB8, integrin β 8 subunit precursor; JUP, junction plakoglobin; NA, not applicable; TAA, tumor-associated self-antigen; TACE, tumor necrosis factor-alpha converting enzyme; TOP2A, topoisomerase IIα.

Figure 1 Intracellular IFN-γ in CD8+ T-cells (A) and IFN-γ producing cells (B and C) from draining LNs of HLA-A2 transgenic mice immunized with single- (A and B) or three-dose (C) vaccination, either in DPX-0907 or conventional emulsion vaccine. Draining LN cells from naïve and vaccinated mice were incubated with either unloaded or peptide-loaded DC and stained by intracellular immunofluorescence or in a DC-ELISPOT assay for detecting induction of IFN-γ.

Notes: *P<0.01, DPX-0907 versus conventional emulsion vaccine; ⁺P=0.02, single dose versus three doses of conventional emulsion vaccine.
Abbreviations: CD, cluster of differentiation; DC, dendritic cell; DPX, DepoVax™; ELISPOT, enzyme-linked immunospot; GM-CSF, granulocyte macrophage colony-stimulating factor; HLA, human leukocyte antigen; IFN, interferon; LN, lymph node; SFU, spot-forming unit.

Figure 2 CD4⁺IL-10⁺ cells from spleen and CD4⁺IFN-γ⁺ cells from draining LNs of mice immunized with three doses of DPX-0907, oil emulsion vaccine or naïve mice. Splenocytes and LN cells from indicated groups of mice were isolated and activated for 48 hours in the presence of peptides and used for staining to detect suppressor Tr1 and effector CD4 T-cells.

Notes: *P=0.03, DPX-0907 versus conventional emulsion vaccine.
Abbreviations: CD, cluster of differentiation; DPX, DepoVax™; IFN, interferon; IL, interleukin; LN, lymph node.

Figure 3 Outline of clinical protocol followed in DPX-0907 trial with details on the time-line for screening, treatment and follow-up of late-stage breast, ovarian, and prostate cancer patients. Blood collected at the indicated time points are used for immune monitoring, and the samples up to study day 73 are analyzed.

Abbreviations: DPX, DepoVax™; F/U, follow-up; N, number.

Table 2 Summary of the immune responses in DPX-0907-treated patients

Positive IR in
Breast cancer	3/3 (100%)
Ovarian cancer	5/6 (83%)
Breast/ovarian cancer	8/9 (89%)
Prostate cancer	3/9 (33%)
All patients	11/18 (61%)
Low dose	5/9 (56%)
High dose	6/9 (67%)
Positive IR detected after
1 vaccination	8/11 (73%)
2 vaccinations	2/11 (18%)
3 vaccinations	1/11 (9%)
Positive IR at
1 time point	2/11 (18%)
2 time points	7/11 (64%)
3 time points	2/11 (18%)
Existing IR at
SD73	7/11 (64%)

Abbreviations: DPX, DepoVax™; IR, immune response; SD, study day.

Table 3 Responders among DPX-0907 vaccine recipients and their immune response to vaccine antigens as determined by MHC-multimer assay and multi-parametric flow cytometry

Patient ID	Cancer type	Vaccine dosage	MHC-multimer		ICS – flow cytometry
			Antigen positive	SD positive	Positive stimulus	SD positive	Multi-cytokine positive
04–06	Breast	0.25 mL	P5	21, 42	P5	42	Yes
			P15	42	Pool	42
01–13	Breast	0.25 mL	None	NA	Pool	21	Yes
05–14	Ovarian	0.25 mL	P4	21, 42	Pool	21, 42	Yes
05–15	Ovarian	0.25 mL	P3	73	None	NA	No
			P7	73
			P13	73
03–17	Prostate	0.25 mL	None	NA	Pool	21, 73	Yes
04–19	Breast	1.0 mL	None	NA	Pool	42, 73	Yes
05–07	Ovarian	1.0 mL	P15	73	Pool	21	Yes
02–09	Ovarian	1.0 mL	P5	42, 73	None	NA	No
			P3	42
01–22	Ovarian	1.0 mL	P5	21, 73	Pool	21, 42, 73	Yes
04–10	Prostate	1.0 mL	P5	21, 42	P13, P15,	42	Yes
			P7	42	Pool	42
			P15	21, 42		42
01–18	Prostate	1.0 mL	P4	42	Pool	21, 42, 73	No
			P7	21, 42, 73

Abbreviations: DPX, DepoVax™; ICS, intracellular cytokine staining; MHC, major histocompatibility complex; NA, not applicable; ID, identification number; SD, study day.

Figure 4 DPX-0907-induced increase in the frequency of antigen-specific CD8⁺ T-cells in vaccinated ovarian, prostate, and breast cancer patients. Patient PBMC were stimulated with indicated peptides for 10 days and were stained with corresponding MHC-multimer reagents to detect CD8⁺ T-cells with peptide-specific TCR repertoire. HIV-multimer served as a negative control and CMV-specific multimer was used on a known CMV-positive donor PBMC as internal positive control for the assay (data not shown).

Notes: Data represent percentage of live gated CD3⁺CD8⁺ T-cells that were positive for MHC-multimer staining.
Abbreviations: CD, cluster of differentiation; CMV, cytomegalovirus; DPX, DepoVax™; HIV, human immunodeficiency virus; MHC, major histocompatibility complex; PBMC, peripheral blood mononuclear cells; TCR, T-cell receptor; ID, identification number; SD, study day.